As the form-factor of mobile wireless platforms is showing a decreasing trend, more and more radio frequency bands are being added, increasing antenna functionalities to be integrated within smaller devices, such as smartphones. Commercially available smartphone antennas currently do not provide the needed broad bandwidth and coverage for multiband applications such as LTE and 4G. As smartphones are becoming thinner and the display is getting larger, the space available for antenna elements is becoming increasingly smaller. This makes it increasingly difficult for a single antenna to cover bandwidths at both the lower frequency bands (e.g., MHz) as well as the higher frequency bands (e.g., GHz). Furthermore, antenna performance becomes compromised due to the close proximity of platform structures that impact antenna characteristics.
Conventionally, antenna switching and tuning techniques have been utilized to cover different frequency bands; however, these techniques introduce loss and latency and may result in nonlinearity and noise under certain operating conditions, making these techniques unsuitable for the high-demands of many smartphone applications. Further, simultaneous multi-band operation is difficult with these conventional switching and tuning techniques. Simultaneous operation also becomes challenging with tunable antenna architectures.
Another issue with many conventional antennas in smaller-form-factor platforms is the ground plane. Conventionally, smaller antennas may need to utilize a larger ground plane, such as the platform chassis, that operates as part of the radiator to achieve acceptable performance. This results in a number of performance issues, including isolation and mutual coupling.
Thus there are general needs for antennas suitable for use in mobile wireless platforms that can support multi-band operation and with a small form factor. There are also general needs for broadband and highly-efficient antennas suitable for use in wireless platforms. There are also general needs for wireless platforms configured for multi-band operation.